Added Dockerfile for building pico-hsm and updated README.md with instructions.

Dockerfile

@@ -0,0 +1,54 @@
+FROM debian:bullseye
+ENV DEBIAN_FRONTEND noninteractive
+RUN apt-get update && apt-get install -y \
+	build-essential \
+	git \
+	cmake \
+	gcc-arm-none-eabi \
+	libnewlib-arm-none-eabi \
+	libstdc++-arm-none-eabi-newlib \
+	python3 \
+	python3-pip
+
+RUN useradd -m builduser
+
+USER builduser
+
+WORKDIR /home/builduser
+
+VOLUME /home/builduser/release
+
+ARG VERSION_PICO_SDK 1.4.0
+
+RUN mkdir -p /home/builduser/Devel/pico
+RUN cd /home/builduser/Devel/pico \
+	&& git clone https://github.com/raspberrypi/pico-sdk.git \
+        && cd pico-sdk \
+        && git checkout $VERSION_PICO_SDK \
+        && git submodule update --init --recursive
+
+RUN pip install cryptography
+
+ARG VERSION_MAJOR 2
+ARG VERSION_MINOR 6
+
+RUN cd /home/builduser \
+	&& git clone https://github.com/polhenarejos/pico-hsm.git \
+	&& cd pico-hsm \
+	&& git checkout v${VERSION_MAJOR}.${VERSION_MINOR} \
+	&& git submodule update --init --recursive \
+	&& mkdir build_release
+
+ENV PICO_SDK_PATH /home/builduser/Devel/pico/pico-sdk
+
+
+
+ARG USB_VID 0xfeff
+ARG USB_PID 0xfcfd
+
+ARG PICO_BOARD waveshare_rp2040_zero 
+
+RUN cd /home/builduser/pico-hsm \
+	&& cd build_release \
+	&& cmake .. -DPICO_BOARD=$PICO_BOARD -DUSB_VID=${USB_VID} -DUSB_PID=${USB_PID} \
+	&& make -kj20